Ammonite faunas of southern Africa and their use in biostratigraphy

Ammonites are extinct, probably squid-like animals that had an external shell that was used for flotation. They are a very useful group to use in dating geological sediments because of their rapid rate of evolution, sometimes as little as 0,5 million years, coupled with a wide geographic distribution.

The main objective of this research programme is to fully describe the ammonite faunas from southern Africa, to compare them with similar faunas from other parts of the world, and to compile a detailed geological calendar based on the ammonite succession. The ultimate aim is to compile a series of atlases to fully illustrate the ammonite faunas from southern Africa, and to integrate the ammonite biozonation with zonations based on other faunas and floras as well as chemical signatures.

The main focus of this work is on the Cretaceous system in KwaZulu-Natal and the Eastern Cape. The Cretaceous Period was a very interesting time in the history of the earth, from both a geological and a biological point of view.

Events of special interest included the opening of the Atlantic Ocean, a world-wide mid-Cretaceous anoxic event, culminating in a mass extinction at the end of the Period. Since initiation of the project in 1966, the area has been mapped in detail, stratigraphic sections were measured at approximately 180 localities, and the systematic description of the fossils is ongoing. Interesting faunal similarities were found in part with the Caucasus region of Georgia, Patagonia, Madagascar, and the Gosau Basin of Austria.

The ammonites became extinct at the end of the Cretaceous Period. Reasons for the extinction are varied; at present the impact theory is the most popular.